1. Field of the Invention
The present invention relates to a multi-cylinder refrigerant gas compressor, preferably adapted for use in automobile air-conditioning system. More specifically, it relates to a swash plate type compressor with a mufflng arrangement for suppressing pulsations in the pressure of a refrigerant gas when discharged after compression.
2. Description of the Related Art
In a multi-cylinder refrigerant gas compressor for use in automobile air-conditioning system, refrigerant gas returning from the air-conditioning system is pumped into and compressed by a multi-cylinder compressing system having pistons operated by an actuator, such as a rotary swash plate. The compressed refrigerant gas is then discharged from the cylinder bores into discharge chambers provided axially at the front and/or rear of a cylinder unit of the compressor. The compressed refrigerant gas is divided and passed through separate discharge passageways of the cylinder block unit, and is then formed into a single mass. Subsequently, the mass of refrigerant gas is sent through a connecting flange element toward a cooling circuit of the air-conditioning system.
During the above-mentioned compression and discharge of the refrigerant gas, pulsation occurs in the pressure of the discharged gas, due to the reciprocating motion of the pistons. The frequency of the pulsation depends on the number of cylinder bores, and the pulsation must be suppressed to prevent noise and vibration. Accordingly, conventionally a muffling chamber is provided in the refrigerant-gas delivery circuit for reducing the pulsation in the pressure of the discharged refrigerant gas.
U.S. Pat. No. 4,610,604 to Iwamori discloses a multi-cylinder swash plate type compressor having a connecting flange which defines therein a muffling chamber and a collision zone. In the compressor, the refrigerant gas compressed by the swash-plate operated piston mechanism is delivered from front and rear discharge chambers as a pair of opposed streams of the compressed refrigerant gas into a collision zone wherein the opposed streams of refrigerant gas are allowed to directly collide, to thus weaken the pulsation in the pressure of the discharged compressed refrigerant gas. The refrigerant gas is then sent toward the muffling chamber, to ensure a complete suppression of the pulsation, and delivered to the cooling circuit via the connecting flange. Nevertheless, the compressor of U.S. Pat. No. 4,610,604 having the above-mentioned muffling and collision chambers is conventionally constructed in such a manner that the compression and discharge capacities exerted by the front chamber are substantially equal to those of the rear chamber of the compressor, and therefore, the opposed streams of the compressed gas are delivered from a pair of coaxially opposed orifices, arranged at two positions spaced equidistantly from the front and rear discharge chambers, into the collision zone, and thus the pulsation in the discharge pressure of the refrigerant gas is not sufficiently weakened. In this connection, if measures are taken to increase the volume of the muffling chamber to an extent such that the pulsation of the discharged refrigerant gas is satisfactorily muffled, the muffling chamber per se becomes very large, and accordingly, the size of the compressor as a whole is increased. As a result, for example, when the compressor is used as a compressing unit of a car airconditioning system, the compressor cannot be mounted in the engine compartment of a small car.